Extended Wigner's friend problem and the internal consistency of standard quantum mechanics

Abstract

The extended Wigner's friend problem deals with two Observers each measuring a sealed laboratory in which a friend is making a quantum measurement. We investigate this problem by relying on the basic rules of quantum mechanics as exposed by Feynman in the well-known "Feynman Lectures on Physics". Although recent discussions have suggested that the extended Wigner's friend problem cannot consistently be described by quantum theory, we show here that a straightforward application of these standard rules results in a non-ambiguous and consistent account of the measurement outcomes for all agents involved.

22 pages, 3 figures

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Cited by in corpus (3)

• A thermodynamically consistent approach to the energy costs of quantum measurements
• Wigner's friends, tunnelling times and Feynman's "only mystery of quantum mechanics"
• Unitary evolution and elements of reality in consecutive quantum measurements